"I could not be more excited about Lupita and Gwendoline joining the cast of Episode VII," said Lucasfilm president Kathleen Kennedy. "It's thrilling to see this extraordinarily talented ensemble taking shape."

Nyong'o won a best supporting actress Oscar earlier this year for her breakout role in "12 Years a Slave." She also had a role in the action thriller "Non-Stop" and will lend her voice to the upcoming remake of "The Jungle Book."

Christie, who plays Brienne of Tarth on HBO's "Game of Thrones," has also been cast in "The Hunger Games: Mockingjay - Part 2."

Directed by J.J. Abrams, "Episode VII" is slated to open in theaters Dec. 18, 2015.